U.S. patent application number 11/216311 was filed with the patent office on 2006-04-13 for apparatus and method for fabricating photonic crystral optical fiber preform.
This patent application is currently assigned to Samsung Electronics Co., LTD. Invention is credited to Soon-Jae Kim, Keun-Deok Park.
Application Number | 20060075787 11/216311 |
Document ID | / |
Family ID | 36143912 |
Filed Date | 2006-04-13 |
United States Patent
Application |
20060075787 |
Kind Code |
A1 |
Kim; Soon-Jae ; et
al. |
April 13, 2006 |
Apparatus and method for fabricating photonic crystral optical
fiber preform
Abstract
Disclosed is an apparatus for fabricating a preform used to
manufacture a photonic crystal optical fiber having multiple holes
extending in a longitudinal direction thereof. The apparatus
includes a housing for containing a raw material for the photonic
crystal optical fiber; a first support member positioned at one end
of the housing; a second support member positioned at the other end
of the housing; and multiple tubes respectively supported by the
first and second support members to be at least partly located
within the housing, wherein diameter of each multiple tube can be
variable selectively depending on an amount of fluid poured through
the open ends of the tubes.
Inventors: |
Kim; Soon-Jae; (Gumi-si,
KR) ; Park; Keun-Deok; (Busan, KR) |
Correspondence
Address: |
CHA & REITER, LLC
210 ROUTE 4 EAST STE 103
PARAMUS
NJ
07652
US
|
Assignee: |
Samsung Electronics Co.,
LTD
|
Family ID: |
36143912 |
Appl. No.: |
11/216311 |
Filed: |
August 31, 2005 |
Current U.S.
Class: |
65/395 |
Current CPC
Class: |
C03B 37/016 20130101;
C03B 2203/14 20130101; C03B 2203/42 20130101 |
Class at
Publication: |
065/395 |
International
Class: |
C03B 37/016 20060101
C03B037/016 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 24, 2004 |
KR |
2004-77246 |
Claims
1. An apparatus for fabricating a preform used to produce a
photonic crystal optical fiber having multiple holes extending in a
longitudinal direction thereof, comprising: a housing for housing a
raw material used to produce the photonic crystal optical fiber; a
first support member disposed at a substantially horizontal
orientation at one end of the housing; a second support member
disposed at a substantially horizontal orientation at the other end
of the housing; and a plurality of multiple tubes supported by the
first and second support members to be at least partly located
within the housing, wherein each of the multiple tubes has one open
end and the portions of the tubes located within the housing are
variable in diameter depending on a pressure of fluid poured
through the open ends of the tubes.
2. An apparatus as claimed in claim 1, further comprising: at least
one pouring tube unit coupled to openings formed in the first
support member so as to supply the fluid into the tubes.
3. An apparatus as claimed in claim 2, wherein the pouring unit
comprises: a pouring spout for receiving the fluid; and multiple
tubes radially extending from the pouring spout to communicate with
the pouring spout.
4. An apparatus as claimed in claim 1, wherein the first and second
support members respectively provide vertically aligned multiple
pairs of openings so that the tubes are inserted into and supported
by corresponding opening pairs at the opposites ends thereof.
5. An apparatus as claimed in claim 4, wherein the first and second
support members respectively comprise multiple openings arranged in
a multiple-ply arrangement.
6. An apparatus as claimed in claim 5, further comprising multiple
pouring tube units coupled to the openings of the corresponding
plies, respectively, to supply the fluid to the tubes.
7. An apparatus as claimed in claim 5, wherein each of the pouring
tube unit comprises: a pouring spout for introducing the fluid; and
multiple tubes radially extending from the pouring spout to
communicate with the pouring spout.
8. A method for fabricating a preform used to produce a photonic
crystal optical fiber having multiple holes extending in a
longitudinal direction thereof, the method comprising the steps of:
providing a plurality of expandable tubes in a substantially
vertical orientation in a housing; selectively pouring a fluid into
the expandable tubes to expand each tube to a predetermined
diameter; providing a sol into the housing and performing a gelling
process of the sol; removing the fluid from the expandable tubes;
and removing the housing to release the gel.
9. The method of claim 8, wherein an amount of the fluid poured
into the expandable tubes is selectively adjusted to control the
diameter of each expandable tube.
10. The method of claim 8, further comprising the step of
performing a drying process, a low-temperature heat treatment
process, a sintering process to the released gel to obtain the
preform.
Description
CLAIM OF PRIORITY
[0001] This application claims priority to an application entitled
"Apparatus for Fabricating Photonic Crystal Optical Fiber Preform,"
filed with the Korean Intellectual Property Office on Sep. 24, 2004
and assigned Serial No. 2004-77246, the contents of which are
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a photonic crystal optical
fiber, and in particular to an apparatus for fabricating a photonic
crystal optical fiber preform.
[0004] 2. Description of the Related Art
[0005] A photonic crystal optical fiber is fabricated from a
transparent glass material and has multiple holes which extend in a
longitudinal direction thereof. Propagation of an optical signal in
such a photonic crystal optical fiber occurs by a photonic band-gap
effect and an effective index, which is discussed in detail by T.
A. Birks et al. in Electronic Letters, Vol. 31(22) p. 1941 (October
1995) and by J. C. Knight et al. in Proceeding of OFC, PD 3-1
(February 1996).
[0006] In the prior art, a glass stacking method, a glass drilling
method, a sol-gel method, etc. are available as means for
fabricating a photonic crystal optical fiber preform. The glass
stacking method involves fabricating a photonic crystal optical
fiber by repeatedly performing the steps of stacking, bundling, and
elongating multiple glass tubes. The glass drilling method requires
forming of multiple holes in a glass rod by drilling. The sol-gel
method includes the steps of: positioning multiple pins in a hollow
cylindrical mold, pouring liquefied sol into the mold, converting
the sol into gel state, and then releasing the gel from the mold.
Then, a series of processes including a drying process, a
low-temperature heat treatment process, and a sintering process are
performed to the released gel to obtain a photonic crystal optical
preform. The characteristics of such a photonic crystal optical
fiber obtained by melting the preform is mainly determined by an
air filling factor (AFF), which indicates a ratio of a diameter of
a hole to a distance between the centers of adjacent holes.
[0007] However, as the conventional sol-gel methods employ pins
having a constant diameter for forming the opening of the photonic
crystal optical preform, there are drawbacks in that it is
difficult to optionally set the diameter of each hole and the wall
thickness between holes (that is, it is difficult to optionally set
an AFF). Further, the shape of gel is frequently collapsed during
the process of removing the pins if the holes are closely
positioned, or if the wall thickness between the holes are
thin.
SUMMARY OF THE INVENTION
[0008] Accordingly, the present invention has been made to solve
the above-mentioned problems occurring in the prior art and
provides additional advantages, by providing an apparatus and
method for fabricating a photonic crystal optical fiber preform,
which allows the diameter of a hole to be adjusted selectively and
in which gel is released easily.
[0009] In one embodiment, there is provided an apparatus for
fabricating a preform for a photonic crystal optical fiber having
multiple holes extending in a longitudinal direction thereof which
includes: a housing for containing a raw material for the photonic
crystal optical fiber; a first support member positioned at one end
of the housing; a second support member positioned at the other end
of the housing; and multiple tubes respectively supported by the
first and second support members to be at least partly located
within the housing, wherein each of the multiple tubes has one open
end and the portions of the tubes located within the housing are
variable in diameter depending on the pressure of fluid poured
through the open ends of the tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The above features and advantages of the present invention
will be more apparent from the following detailed description taken
in conjunction with the accompanying drawings, in which:
[0011] FIG. 1 is a cross-sectional view of a photonic crystal
optical fiber preform according to an embodiment of the present
invention;
[0012] FIG. 2 is a vertical sectional view of an apparatus for
fabricating a photonic crystal optical fiber according to an
embodiment of the present invention;
[0013] FIG. 3 is a top plan view of the fabrication apparatus of
FIG. 2 in a state in which first and third pouring tube units are
removed;
[0014] FIG. 4 is a top plan view of the fabrication apparatus of
FIG. 2 in a state in which the first pouring tube unit is connected
to a first support plate;
[0015] FIG. 5 is a perspective view of the first pouring tube
unit;
[0016] FIG. 6 is a top plan view of the apparatus shown in FIG. 2
in a state in which the second pouring tube unit is connected to
the first support plate; and
[0017] FIG. 7 is a top plan view of the apparatus shown in FIG. 2
in a state in which the third pouring tube unit is connected to the
first plate.
DETAILED DESCRIPTION
[0018] Hereinafter, embodiments of the present invention will be
described with reference to the accompanying drawings. For the
purposes of clarity and simplicity, a detailed description of known
functions and configurations incorporated herein will be omitted as
it may make the subject matter of the present invention
unclear.
[0019] FIG. 1 shows a photonic crystal optical fiber preform
according to an embodiment of the present invention. As shown, the
preform 100 is formed generally in a cylindrical rod shape from a
glass material and has multiple cylindrical holes 110 extending
therethrough in a longitudinal direction. The holes 110 are
arranged around a core region positioned at the center of the
preform. In particular, the holes 110 are arranged in a three-ply
arrangement around the core region, in which each ply takes a form
of regular hexagonal. The first ply 130 surrounding the core region
consists of six holes 110, the second ply 140 surrounding the first
ply 130 consists of twelve holes 110, and the third ply 150
surrounding the second ply 140 consists of eighteen holes 110. The
number of the plies of the holes 110 can be selectively increased
or decreased, and each ply may be in a form of square shape.
[0020] FIG. 2 shows an apparatus for fabricating a photonic crystal
optical fiber preform according to an embodiment of the present
invention. As shown, the fabrication apparatus 200 includes a
molding means used in the gelling process during fabrication
according to a sol-gel method. In particular, the fabrication
apparatus 200 includes a housing 210, first and second supporting
members 220, 230, multiple tubes 240, and first to third pouring
tube units 250, 260, 270.
[0021] The housing 210 is in a cylindrical tubular shape having
opened opposite ends and contains sol 290, which is the raw
material of a photonic crystal optical fiber preform. The housing
210 has a sol pouring spout 215 on its upper part for receiving the
sol 290 from the outside. The sol spout 215 takes a form of elbow
with a cylindrical tube, wherein one open end of the spout is
externally exposed and the other open end is exposed within the
housing 210. The sol 290 is filled to the bottom of the housing 210
through the sol pouring spout 215.
[0022] The first support member 220 is positioned on the open top
end of the housing 210 and is in a form of circular plate having
multiple cylindrical holes 222. The first support member 220 closes
the top open end of the housing, and the arrangement of the holes
222 are identical to that of the holes 110 shown in FIG. 1.
[0023] FIG. 3 is a top plan view showing the fabrication apparatus
200 in a state in which the first to third pouring tube units 250,
260, 270 are removed. As shown, the first support member 220 has
multiple holes 222 arranged around the core area located at the
center of the first support member 220 to form multiple plies 224,
226, 228. In particular, the holes 222 are arranged in a three-ply
arrangement around the core area with each ply having a hexagonal
form. The first ply 224 surrounding the core area consists of six
holes 222, the second ply 226 surrounding the first ply 224
consists of twelve holes 222, and the third ply 228 consists of
eighteen holes 222. It should be noted that number of holes in FIG.
3 is shown for illustrative purposes. Thus, the number of holes
should not limit the scope of the present invention.
[0024] Returning back to FIG. 2, the second support member 230 is
located at the bottom open end of the housing 210 and is in a form
of circular plate having multiple cylindrical holes 235. The second
support member 230 has a same form as the first support member 220,
and the holes 230 in the second support member 230 are vertically
aligned with the holes 222 in the first support member 220. As the
second support member 230 covers the bottom open end of the housing
210, the sol 230 flowed into the interior of the housing 210
through the sol pouring spout 215 is contained in the housing.
[0025] The multiple tubes may be cylindrical tubes each formed from
an easily bendable and diametrically expandable and shrinkable
material, for example, cylindrical rubber tubes. Each tube 240 is
inserted into and supported by a corresponding pair of vertically
aligned holes in the first and second support members 220, 230, at
the opposite ends thereof. In order to facilitate the release of
gel, the top end of each tube 240 may be attached to the inner
periphery of a corresponding hole in the first supporting member
220 while the lower end of the tube 240 may be inserted into a
corresponding hole in the second supporting member 230. The tubes
240 may be arranged in a three-ply arrangement around the core area
similar to the arrangements of holes in the first support plate 220
and the second support plate 230, with each ply taking a hexagonal
form.
[0026] For example, the first ply surrounding the core area
consists of six tubes 240, the second ply surrounding the first ply
consists of twelve tubes 240, and the third ply surrounding the
second ply consists of eighteen tubes 240. Each tube is sealed by a
corresponding stopper 280 at the lower end thereof. The portion of
the tube located between its opposite ends supported by the holes,
i.e., the portion positioned within the housing 210 may be variable
in diameter depending on the pressure of the fluid introduced
through the open top end thereof.
[0027] By curing the sol 290 contained in the housing 210 in a
state in which the diameter of the tube 240 has been changed to a
preset diameter, it is possible to obtain a gel having multiple
holes each having a preset diameter. Hence, it is possible to
optionally set the diameter of each hole formed in the gel and the
wall thickness between the holes. In addition, the stress applied
to the walls between the holes in the process of releasing the
tubes 240 can be minimized by employing the tubes 240 formed from a
freely bendable material. Further, it is possible to reduce the
wall thickness. The shape of the gel is identical to that of the
preform shown in FIG. 1, and subsequently by performing a drying
process, a low-temperature heat treatment process and a sintering
process to the gel, a preform 100 as shown FIG. 1 can be
obtained.
[0028] The first to third pouring tube units 250, 260, 270 are
fixed to the top surface of the first support member 220 such that
they are connected to the holes 222 in the first support member
220, and fluid is supplied to the tubes 240 through the first to
third pouring tube units 250, 260, 270. The first to third pouring
tube units 250, 260, 270 respectively consist of cylindrical tube
shaped pouring spout 252, 262, 272 and elbow-shaped cylindrical
tubes 254, 264, 274 radially extending to communicate with the
cylindrical tube shaped pouring spouts 252, 262, 272. The tubes
254, 264, 274 are connected to and communicate with the pouring
spouts 252, 262, 272, and the tip ends of the tubes 254, 264, 274
are respectively connected to corresponding holes 222 in the first
support member 220 to communicate with corresponding tubes 240.
[0029] FIG. 4 is a top plan view showing the connection state of
the first pouring tube unit 250 to the first support plate 220, and
FIG. 5 is a perspective view showing the first pouring tube unit
250. As shown, the tip ends of the six tubes 254 of the first
pouring tube unit 250 are connected to the holes 222 of the first
ply 224 in the first plate 220. Each tube 254 of the first pouring
tube unit 250 is extended in the diametrical direction of the
pouring spout 252 and then downwardly bent in the longitudinal
direction of the pouring spout 252.
[0030] FIG. 6 is a top plan view showing the connection state of
the second pouring tube unit 260 to the first support plate 220. As
shown, the tip ends of the twelve tubes 264 of the second pouring
tube unit 260 are connected to the holes 222 of the second ply 226
in the first support plate 220. Although not shown in FIG. 6, the
second pouring tube unit 260 covers the first pouring tube unit
250.
[0031] FIG. 7 is a top plan view showing the connection of the
third pouring tube unit 270. As shown, the tip ends of the eighteen
tubes 274 of the third pouring tube unit 270 are connected to the
holes 222 of the third ply 228 in the first support plate 220.
Although not shown in FIG. 7, the third pouring tube unit 270
covers the second pouring tube unit 260.
[0032] Now, the processes of forming gel using the fabrication
apparatus 200 and releasing the gel are described hereinafter with
reference to FIG. 2.
[0033] First, fluid is poured into the pouring spouts 252, 262, 272
of the first to third pouring tube units 250, 260, 270 to expand
each tube 240 to a predetermined diameter. At this time, by
selectively adjusting the amount of the fluid pouring into each of
the first to third pouring tube units 250, 260, 270, it is possible
to make the tubes 240 of the first to third plies have different
diameters from each other, or to make the tubes 240 of any one ply
have a diameter different from the remaining tubes.
[0034] Next, sol 290 is poured into the sole pouring spout 215 to
be filled within the housing 210 to a preset height from the bottom
of the housing 210.
[0035] Then, if the gelling process of the sol 290 is completed,
the fluid in the tubes 240 are removed through the pouring spouts
252, 262, 272 of the first to third pouring tube units 250, 260,
270, thereby allowing the tubes 240 to shrink to the state prior to
expansion.
[0036] Then, the stoppers 280 connected to the lower ends of the
tubes 240 are removed.
[0037] Then, the housing 210 is lifted upwardly to release the gel
from the housing 210.
[0038] Thereafter, by performing a drying process, a
low-temperature heat treatment process, a sintering process, etc.
to the released gel, a preform 100 as shown in FIG. 1 can be
obtained.
[0039] As described above, the inventive apparatus for fabricating
a photonic crystal optical preform has an advantage in that the
diameters of holes formed in gel and the wall thickness (of AFF)
between holes can be optionally set by employing expandable and
shrinkable tubes, and in that the wall thickness between the holes
can be reduced as compared to the prior art by minimizing the
stress developed between the holes and tubes.
[0040] While the invention has been shown and described with
reference to certain preferred embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
* * * * *